Work vehicle and wheel loader

ABSTRACT

A work vehicle includes an engine, an exhaust gas post-processing device, an engine room, a cooling fan, a cooling unit and a first exhaust pipe. The exhaust gas post-processing device includes a diesel particulate filtering device, a selective catalyst reduction device, a connecting pipe connecting the diesel particulate filtering device and the selective catalyst reduction device, and an injection device configured and arranged to inject a reducing agent into the connecting pipe. The engine room accommodates the engine and the exhaust gas post-processing device. The cooling fan is configured to suck in air from one side and to exhaust air from another side to produce an air flow. The cooling unit is disposed on the one side of the cooling fan. The first exhaust pipe has one end arranged to suck in air around the injection device and another end located between the cooling fan and the cooling unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National stage application of InternationalApplication No. PCT/JP2013/058706, filed on Mar. 26, 2013.

BACKGROUND

1. Field of the Invention

The present invention relates to a work vehicle and a wheel loader.

2. Background Information

A wheel loader includes an engine room containing an engine to the rearof a cab (Japanese Laid-Open Patent Publication No. H8-276755).Recently, exhaust gas post-processing devices have been mounted on wheelloaders for processing exhaust gas from the engine. The exhaust gaspost-processing device includes mainly a diesel particulate filteringdevice and is usually contained inside the engine room.

A hydraulic excavator described in Japanese Laid-open Patent PublicationNo. 2011-140853 is provided with a nitrogen oxide purifying device as aselective catalyst reduction device as the exhaust gas post-processingdevice. These exhaust gas post-processing devices are typically disposedabove the engine to be provided in the exhaust gas path.

SUMMARY

As described above, while the diesel particulate filter is used as theexhaust gas post-processing device, the provision of a selectivecatalyst reduction device in addition to the diesel particulate filterin the wheel loader is considered to further purify the exhaust gas. Inthis case, an injection device injects the reducing agent into theexhaust gas flowing inside a connecting pipe that connects the dieselparticulate filtering device and the selective catalyst reductiondevice. As a result, the nitrogen oxides in the exhaust gas exhaustedfrom the engine are reduced to nitrogen.

However, there is a problem that since the diesel particulate filteringdevice and the selective catalyst reduction device produce heat whileoperating, the heat from the devices causes the injection device tobecome hot thus causing sealing material and the like of the injectiondevice to degrade. Furthermore, Urea aqueous is generally used as thereducing agent to be injected by the injection device. The urea aqueouschanges to ammonia when heated. Since ammonia has very strongalkalinity, there is a problem that the durability of the injectiondevice and the like is reduced. This type of problem is not limited towheel loaders, and also may occur in other work vehicles.

An object of the present invention is to prevent a rise in thetemperature of the injection device.

(1) A work vehicle according to a first aspect of the present inventionis equipped with an engine, an exhaust gas post-processing device, anengine room, a cooling fan, a cooling unit, and a first exhaust pipe.The exhaust gas post-processing device includes a diesel particulatefiltering device, a selective catalyst reduction device, a connectingpipe, and an injection device. The connecting pipe connects the dieselparticulate filtering device and the selective catalyst reductiondevice. The injection device injects a reducing agent into theconnecting pipe. The engine room accommodates the engine and the exhaustgas post-processing device. The cooling fan sucks in air from one sideand exhausts air from another side to produce an air flow. The coolingunit is disposed on the one side of the cooling fan. The first exhaustpipe has one end and another end. The one end of the first exhaust pipesucks in air around the injection device. The another end of the firstexhaust pipe is located between the cooling fan and the cooling unit.

According to this configuration, the another end of the first exhaustpipe is located between the cooling unit and the cooling fan which is aregion of negative pressure when the cooling fan is operating. As aresult, the first exhaust pipe acts to suck in the air around theinjection device from the one end and exhaust the air from the anotherend. Consequently, the area around the injection device in the engineroom has negative pressure, and the air taken in from outside of theengine room flows into the area around the injection device. As aresult, the injection device is cooled by the cooling air that flowsfrom the outside toward the one end of the first exhaust pipe.

(2) The work vehicle preferably is further equipped with a partitioningmember. The partitioning member includes a first partition part and asecond partition part. The first partition part is disposed between theinjection device and the diesel particulate filtering device. The secondpartition part is disposed between the injection device and theselective catalyst reduction device.

According to this configuration, the injection device is at leastcovered by the partitioning member on the diesel particulate filteringdevice side and the selective catalyst reduction device side. As aresult, the one end of the first exhaust pipe is able to suck in airaround the injection device efficiently and accordingly is able tofurther cool the injection device. Further, since the first partitionpart of the partitioning member is disposed between the injection deviceand the diesel particulate filtering device, radiant heat radiating fromthe diesel particulate filtering device toward the injection device canbe blocked by the first partition part. According to this configuration,a rise in the temperature of the injection device due to radiant heatfrom the diesel particulate filtering device can be prevented.Furthermore, since the second partition part of the partitioning memberis disposed between the injection device and the selective catalystreduction device, radiant heat radiating from the selective catalystreduction device toward the injection device can be blocked by thesecond partition part. Accordingly, a rise in the temperature of theinjection device due to radiant heat from the selective catalystreduction device can be prevented.

(3) The one end of the first exhaust pipe is preferably located above anattachment part of the injection device to the connecting pipe.According to this configuration, the vicinity of the injection devicecan be cooled more effectively.

(4) The one end of the first exhaust pipe is preferably located in anaccommodating space defined by the first partition part and the secondpartition part. According to this configuration, the one end of thefirst exhaust pipe is able to more effectively suck in air around theinjection device since the injection device is disposed inside theaccommodating space.

(5) The work vehicle preferably is further equipped with a secondexhaust pipe. The second exhaust pipe has one end that is located abovethe connecting pipe inside the engine room, and another end that islocated between the cooling fan and the cooling unit. According to thisconfiguration, the another end of the second exhaust pipe is locatedbetween the cooling unit and the cooling fan which is a region ofnegative pressure when the cooling fan is operating. As a result, thesecond exhaust pipe acts to suck air inside the engine room from the oneend and exhaust the air from the another end. Consequently, hot airinside the engine room can be exhausted to the outside.

(6) The connecting pipe is preferably disposed so that a longitudinaldirection thereof is aligned in the vehicle width direction, and theinjection device is disposed on a first side of the connecting pipe asseen from the rear.

According to this configuration, the injection device is disposedbetween the connecting pipe and an vehicle cover. As a result, the areaaround the injection device is covered by the connecting pipe and thevehicle cover in addition to the abovementioned partitioning member.Consequently, the first exhaust pipe is able to suck in the air aroundthe injection device from the one end more effectively to allow for morecooling of the injection device.

(7) The injection device preferably injects the reducing agent at anupstream side of the exhaust gas flowing inside the connecting pipe.According to this configuration, the reducing agent can be sufficientlymixed with the exhaust gas inside the connecting pipe.

(8) The diesel particulate filtering device and the selective catalystreduction device preferably are disposed with the longitudinaldirections thereof aligned in the vehicle width direction.

(9) The injection device is preferably disposed between the dieselparticulate filtering device and the selective catalyst reduction devicein the front-back direction, and the partitioning member furtherincludes a third partition part disposed above the injection device.

According to this configuration, the injection device is covered by thepartitioning member in the front, in the rear, and on top. Consequently,the first exhaust pipe is able to suck in the air around the injectiondevice from the one end more effectively to allow for improved coolingefficiency of the injection device.

(10) The work vehicle preferably further includes a top plate thatdefines an upper plane of the engine room. The exhaust gaspost-processing device is disposed above the engine and the top platehas a first ventilation part that includes a plurality of through-holes.

According to this configuration, due to the first exhaust pipe suckingin air around the injection device, outside air can enter the injectiondevice through the first ventilation part and the injection device canbe cooled by air from outside.

(11) The top plate preferably further has a sloping part having a heightthat descends toward the rear. The first ventilation part is formed inthe sloping part.

According to this configuration, since mainly the rear part of the topplate of the engine room is provided with the sloping part having aheight that descends toward the rear, the visibility to the rear can beassured while the top plate of the engine room is high. Since the firstventilation part is formed in the sloping part, the occupied surfacearea of the first ventilation part can be made wider than if the firstventilation part is formed in a horizontal part and the intrusion ofrainwater can be suppressed.

(12) The sloping part of the top plate preferably defines a rear partupper plane of the engine room. The top plate has a flat part thatextends horizontally from the front edge of the sloping part toward thefront and defines a front part upper plane of the engine room. Accordingto this configuration, the capacity of the engine room is increased bythe amount in which the flat part projects upward.

(13) Preferably, the top plate further includes a pair of side wallparts that extend downward from both side edges of the flat part and thesloping part. The side wall parts include a second ventilation parthaving a plurality of through-holes.

According to this configuration, since the top plate has the secondventilation part in addition to the first ventilation part, air is ableto flow more smoothly between the inside and the outside of the engineroom. As a result, the injection device can be cooled more effectively.

(14) Preferably, the through-holes of the second ventilation part haveeave parts. According to this configuration, water from rain and thelike can be prevented from entering the engine room through the secondventilation part.

(15) The work vehicle preferably is equipped with a cooling room and apartition wall. The cooling room is disposed to the rear of the engineroom and accommodates a cooling unit. The partition wall separates theengine room and the cooling room.

(16) A wheel loader according to a second aspect of the presentinvention is equipped with an engine, an exhaust gas post-processingdevice, an engine room, a cooling room, a partition wall, a cooling fan,and a first exhaust pipe. The exhaust gas post-processing deviceincludes a diesel particulate filtering device, a selective catalystreduction device, a connecting pipe, and an injection device. Theconnecting pipe connects the diesel particulate filtering device and theselective catalyst reduction device. The injection device injects areducing agent into the connecting pipe. The engine room accommodatesthe engine and the exhaust gas post-processing device. The cooling roomis disposed to the rear of the engine room and accommodates a coolingunit. The partition wall separates the engine room and the cooling room.The cooling fan is disposed to the rear of the cooling unit in thecooling room and exhausts air inside the cooling room to the rear. Thefirst exhaust pipe has one end and another end. The one end of the firstexhaust pipe sucks in air around the injection device. The another endof the first exhaust pipe is located between the cooling fan and thecooling unit.

According to this configuration, the another end of the first exhaustpipe is located between the cooling unit and the cooling fan which is aregion of negative pressure when the cooling fan is operating. As aresult, the first exhaust pipe acts to suck in the air around theinjection device from the one end and exhaust the air from the anotherend. Consequently, the area around the injection device in the engineroom has negative pressure, and air taken in from outside of the engineroom flows around the injection device. As a result, the injectiondevice is cooled by the cooling air that flows from the outside towardthe one end of the first exhaust pipe.

According to the present invention, a rise in temperature of theinjection device can be prevented.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of the wheel loader as seen from the leftrear.

FIG. 2 is a side cross-section of the rear vehicle body as seen from theleft side.

FIG. 3 is a perspective view of the exhaust gas post-processing deviceas seen from the left rear.

FIG. 4 is a perspective view of a detail around the injection device asseen from the right front.

FIG. 5 is a plan view of the detail around the injection device.

FIG. 6 is a plan view of the rear vehicle body when the top plate isremoved.

FIG. 7 is a perspective view of the top plate as seen from the leftrear.

FIG. 8 is a cross-section of the left side of the top plate as seen fromthe rear.

FIG. 9 is a side cross-section of a drainage mechanism as seen from theleft side.

FIG. 10 is a perspective view of the drainage mechanism as seen from theright rear.

FIG. 11 is a perspective view of a water conveyance member disposed onthe left side as seen from the right rear.

DETAILED DESCRIPTION OF EMBODIMENTS

An embodiment of a wheel loader according to the present invention willbe explained below with reference to the drawings. FIG. 1 is aperspective external view of a wheel loader 1 as seen from the leftrear. In the following explanation, “front” and “rear” refer to thefront and the rear of a vehicle body 3. In the following explanation,“right,” “left,” “up,” and “down” indicate directions relative to astate of looking forward from the operating cabin, and “vehicle widthdirection” and “crosswise direction” have the same meaning. Further,“width” signifies a length in the crosswise direction.

As illustrated in FIG. 1, the wheel loader 1 includes working equipment2, the vehicle body 3, front wheels 4, and rear wheels 5. The wheelloader 1 is capable of traveling due to the rotation of the front wheels4 and the rear wheels 5, and desired work can be conducted using theworking equipment 2.

The working equipment 2 is a mechanism driven by operating fluidpressurized by a pump, and is disposed at the front of the vehicle body3. The working equipment 2 includes a bucket 2 a, a boom (not shown), alift cylinder (not shown), and a bucket cylinder 2 b. The bucket 2 a isattached to the tip of the boom. The boom is a member for lifting thebucket 2 a and is mounted at the front part of a belowmentioned frontvehicle body 3 a. The lift cylinder drives the boom with pressure oildischarged from a working equipment pump. The bucket cylinder 2 b drivesthe bucket 2 a with pressure oil discharged from the working equipmentpump.

The vehicle body 3 includes the front vehicle body 3 a and a rearvehicle body 3 b. The front vehicle body 3 a and the rear vehicle body 3b are coupled to each other in a manner that allows swinging in thecrosswise direction. The working equipment 2 and the front wheels 4 areprovided on the front vehicle body 3 a, and the rear wheels 5 areprovided on the rear vehicle body 3 b.

The rear vehicle body 3 b includes a rear frame 6, a cab 7, an operatingfluid tank 8, an engine room 9, a cooling room 10, and a cooling fan 11.The rear frame 6 is a frame that constitutes the entire shape of therear vehicle body 3 b, and supports the rear wheels 5, the cab 7, theoperating fluid tank 8, an engine 12 (see FIG. 2), and a cooling unit 18(see FIG. 2).

An operating cabin is provided inside the cab 7, and various operatingmembers and an operating panel are provided inside the cab 7. Theoperating fluid tank 8 is disposed to the rear of the cab 7, and aplurality of hydraulic pumps (not shown) are disposed below theoperating fluid tank 8. Operating fluid for driving the workingequipment 2 and the like is accumulated in the operating fluid tank 8,and the operating fluid is supplied to the working equipment 2 and thelike by the hydraulic pumps.

FIG. 2 is a side cross-section of the rear vehicle body 3 b as seen fromthe left rear. As illustrated in FIG. 2, the engine room 9 is disposedto the rear of the operating fluid tank 8, and has a front plane definedby the operating fluid tank 8, side planes defined by a vehicle cover 9a (see FIG. 1), a rear plane defined by a partition wall 9 b, and anupper plane defined by a top plate 9 c.

The engine room 9 accommodates the engine 12 and an exhaust gaspost-processing device 13. The engine room 9 further accommodates a belt12 a and the like for transmitting torque from the engine 12 toauxiliary equipment. The engine 12 is disposed in a lower part of theengine room 9 and is an engine in which the crankshaft extends in thefront-back direction, that is, a so-called vertical mounted engine.

The exhaust gas post-processing device 13 accommodated in the engineroom 9 is disposed in an upper part of the engine room 9. Specifically,the exhaust gas post-processing device 13 is disposed above the engine12. FIG. 3 is a perspective view of the exhaust gas post-processingdevice 13 as seen from the left rear. As illustrated in FIG. 3, theexhaust gas post-processing device 13 includes, in order of the flow ofthe exhaust gas, a diesel particulate filtering device 13 a, aconnecting pipe 13 b, and a selective catalyst reduction device 13 c. Aninjection device 14 is attached to the connecting pipe 13 b.

The diesel particulate filtering device 13 a is coupled to the engine 12via a pipe 13 d, and treats exhaust gas emitted from the engine 12.Specifically, the diesel particulate filtering device 13 a is a devicethat collects, in a filter, particulate matter such as soot in theexhaust gas emitted from the engine 12. The diesel particulate filteringdevice 13 a burns the collected particulate matter with a heaterprovided with the filter. The diesel particulate filtering device 13 ais mounted on a supporting member and the like attached to the rearframe 6.

The connecting pipe 13 b connects the diesel particulate filteringdevice 13 a and the selective catalyst reduction device 13 c. Theconnecting pipe 13 b has a first bend section 13 e, a linear section 13f, and a second bend section 13 g, and the entire connecting pipe 13 bforms an S shape. The first bend section 13 e is connected to an exhaustgas outlet 13 h of the diesel particulate filtering device 13 a, and thesecond bend section 13 g is connected to an exhaust gas inlet 13 i ofthe selective catalyst reduction device 13 c. The linear section 13 fextends between the first bend section 13 e and the second bend section13 g. The longitudinal direction of the connecting pipe 13 b is disposedso as to be aligned in the vehicle width direction. The direction inwhich the linear section 13 b extends is the longitudinal direction ofthe connecting pipe 13 b.

The injection device 14 is disposed on the right side (example of afirst side) of the connecting pipe 13 b. That is, the injection device14 is attached to the right side surface of the first bend section 13 e.The injection device 14 is a device that injects a urea aqueoussolution, which is fed from a urea aqueous solution tank (not shown)disposed on the outside of the engine room 9 and through a urea aqueoussolution pipe 14 a (see FIG. 4), into the connecting pipe 13 b in orderto mix the urea aqueous solution into the exhaust gas as a reducingagent. The mixed urea aqueous solution is hydrolyzed to become ammonia,and the ammonia is fed with the exhaust gas through the connecting pipe13 b to the selective catalyst reduction device 13 c.

The selective catalyst reduction device 13 c is a device that uses theurea aqueous solution from the urea water injection device 14 as thereducing agent to purify by reduction the nitrogen oxides in the exhaustgas. The selective catalyst reduction device 13 c is mounted on asupporting member and the like in the same way as the diesel particulatefiltering device 13 a.

The diesel particulate filtering device 13 a and the selective catalystreduction device 13 c are disposed parallel to each other. Specifically,the diesel particulate filtering device 13 a and the selective catalystreduction device 13 c are both substantially cylindrical. The directionthat the center axes of the diesel particulate filtering device 13 a andthe selective catalyst reduction device 13 c extends is the longitudinaldirection of the diesel particulate filtering device 13 a and theselective catalyst reduction device 13 c. The longitudinal direction ofthe devices extends substantially parallel to each other in thecrosswise direction. The linear section 13 f of the connecting pipe 13 bis also substantially cylindrical and the longitudinal direction extendsin the crosswise direction as described above. Specifically, the centeraxis of the linear section 13 f of the connecting pipe 13 b issubstantially parallel to the center axes of the diesel particulatefiltering device 13 a and the selective catalyst reduction device 13 c.

FIG. 4 is a perspective view of a detail around the injection device 14as seen from the right front, and FIG. 5 is a plan view of the detailaround the injection device 14. As illustrated in FIGS. 4 and 5, apartitioning member is disposed so as to cover the injection device 14in the front, the rear, and on the top. The partitioning member includesa first partition plate 16 and a second partition plate 17. The firstpartition plate 16 and the second partition plate 17 are disposed in arow in the front-back direction. The first partition plate 16 isdisposed in front of the second partition plate 17. A partition plate isdivided into two to constitute the first partition plate 16 and thesecond partition plate 17, and an interval between the first partitionplate 16 and the second partition plate 17 is provided to create a gapfor pipes and the like to pass through.

The first partition plate 16 has a base part 16 a and a peripheral wallpart 16 b, and is fixed to the rear frame 6 using a mounting bracket 6 aand bolts 6 b. The first partition plate 16 has heat shieldingproperties and is formed, for example, by a steel plate treated with aheat resistant coating. The base part 16 a of the first partition plate16 is a plate that extends in the front-back direction from the frontedge part of the engine room 9 to near the injection device 14, and hasa substantially rectangular shape. A rear edge part of the base part 16a is cut into a fan shape so that the right side surface of theinjection device 14 is exposed when the vehicle cover 9 a is removed.That is, the base part 16 a does not extend to the side of the injectiondevice 14.

The base part 16 a is disposed between the selective catalyst reductiondevice 13 c and the vehicle cover 9 a. The urea aqueous solution pipe 14a extends between the base part 16 a and the vehicle cover 9 a. Thus,radiant heat radiating toward the urea aqueous solution pipe 14 a fromthe selective catalyst reduction device 13 c can be blocked andconsequently the urea aqueous solution flowing inside the urea aqueoussolution pipe 14 a can be prevented from changing to ammonia. Further,radiant heat radiating toward the vehicle cover 9 a from the selectivecatalyst reduction device 13 c can be blocked and consequently damage tothe coating of the vehicle cover 9 a can be prevented. The urea aqueoussolution pipe 14 a is supported by a plurality of mounting brackets 6 c.The urea aqueous solution pipe 14 a is supported by the mountingbrackets 6 c to maintain a certain distance from the first partitionplate 16. The mounting brackets 6 c extend upward from the rear frame 6and are slanted in a direction away from the first partition plate 16.The mounting brackets 6 c are disposed a certain distance away from eachother in the front-back direction.

The peripheral wall part 16 b of the first partition plate 16 extendsfrom the rear edge of the base part 16 a toward the left side and coversthe injection device 14 from the front thereof to the top of theinjection device 14 so as to face the injection device 14. That is, theperipheral wall part 16 b has a second partition part 16 b 1 that is aportion disposed between the injection device 14 and the selectivecatalyst reduction device 13 c, and a third partition part 16 b 2 thatis a portion disposed between the injection device 14 and the top plate9 c. The peripheral wall part 16 b extends from the base part 16 a tonear the right side surface of the connecting pipe 13 b. The peripheralwall part 16 b also extends substantially along the contour of the rightside surface of the connecting pipe 13 b. As a result, the left side,the front side, and the top of the injection device 14 can be covered bythe peripheral wall part 16 b and the right side surface of theconnecting pipe 13 b.

The second partition plate 17 has a base part 17 a and a peripheral wallpart (example of a first partition part) 17 b, and is fixed to thevehicle cover 9 a using bolts and the like. The vehicle cover 9 a isdivided into a plurality of portions and each of the portions can beopened and closed independently in order to facilitate access to theinside parts (engine room 9 and cooling room 10) of the rear vehiclebody 3 b. The portion of the vehicle cover 9 a supporting the secondpartition plate 17 is fixed to the rear frame 6 via a hinge at the frontedge part of the engine room and can be opened and closed around thehinge (see FIG. 7). Maintenance of the injection device 14 and the likeis facilitated since the second partition plate 17 is also pulled awaywhen the vehicle cover 9 a is opened. The second partition plate 17 hasheat shielding properties and is formed, for example, by a steel platetreated with a heat resistant coating.

The base part 17 a of the second partition plate 17 is a plate thatextends in the front-back direction from near the injection device 14 tothe rear edge part of the engine room 9, and has a rectangular shape.The front edge of the base part 17 a is located to the rear of theinjection device 14. The base part 17 a is disposed between the dieselparticulate filtering device 13 a and the vehicle cover 9 a. As aresult, radiant heat radiating toward the vehicle cover 9 a from thediesel particulate filtering device 13 a can be blocked and consequentlydamage to the coating of the vehicle cover 9 a can be prevented.

The peripheral wall part 17 b of the second partition plate 17 extendsfrom the front edge of the base part 17 a toward the left side andcovers the injection device 14 from the rear thereof so as to face theinjection device 14. That is, the peripheral wall part 17 b is disposedbetween the injection device 14 and an exhaust gas outlet 13 h of thediesel particulate filtering device 13 a. The peripheral wall part 17 bextends from the base part 17 a to near the right side surface of theconnecting pipe 13 b.

As described above, the injection device 14 is disposed in anaccommodating space S defined by the peripheral wall part 16 b of thefirst partition plate 16, the peripheral wall part 17 b of the secondpartition plate 17, the vehicle cover 9 a, and the connecting pipe 13 b.

As illustrated in FIG. 2, the cooling room 10 is disposed to the rear ofthe engine room 9, and the cooling unit 18 is accommodated inside thecooling room 10. The cooling unit 18 is a unit for reducing thetemperature of liquids or gases flowing inside the cooling unit 18, andmay be exemplified by a condenser or a radiator and the like. Thecooling room 10 has a front plane defined by the partition wall 9 b,side planes defined by the vehicle cover 9 a, and a rear plane definedby a grille 21. Further, the upper plane of the cooling room 10 isdefined by the top plate 9 c. Air inside the cooling room 10 isexhausted to the outside in the rear through an opening part of thegrille 21 due to the cooling fan 11 being rotated.

FIG. 6 is a plan view of the rear vehicle body 3 b when the top plate 9c is removed. As illustrated in FIG. 6, a first exhaust pipe 19 and asecond exhaust pipe 20 are disposed so as to straddle the engine room 9and the cooling room 10. The first exhaust pipe 19 is a substantiallylinear pipe having one end 19 a and another end 19 b. The one end 19 aof the first exhaust pipe 19 is located in the engine room 9, and theanother end 19 b of the first exhaust pipe 19 is located in the coolingroom 10. The first exhaust pipe 19 passes through the partition wall 9 bto extend in the front-back direction on the right side and above theengine room 9 and the cooling room 10.

Specifically, the one end 19 a of the first exhaust pipe 19 is locatednear the injection device 14. One end part 19 c that includes the oneend 19 a of the first exhaust pipe 19 bends toward the outside.Consequently, the one end 19 a of the first exhaust pipe 19 is disposedto face the accommodating space S that accommodates the injection device14. The one end 19 a of the first exhaust pipe 19 is located near enoughto the injection device 14 to allow air inside the accommodating space Sto be sucked in. Specifically, the one end 19 a is preferably locatedabove an attachment part of the injection device 14 to the connectingpipe 13 b, or more preferably the one end 19 a is located inside theaccommodating space S.

The another end 19 b of the first exhaust pipe 19 is located between thecooling fan 11 and the cooling unit 18. Another end part 19 d thatincludes the another end 19 b of the first exhaust pipe 19 bendsdownward and to the inside so that the another end 19 b of the firstexhaust pipe 19 is located between the cooling fan 11 and the coolingunit 18. The cooling fan 11 produces an air flow toward the rear.Specifically, the cooling fan 11 sucks in air from the front side (oneside) of the cooling fan 11 and exhausts air from the rear side (anotherside) of the cooling fan 11. Since the cooling unit 18 is disposed onthe front side of the cooling fan 11, negative pressure occurs betweenthe cooling fan 11 and the cooling unit 18. As a result, when thecooling fan 11 is operating, the first exhaust pipe 19 acts to suck inair from the one end 19 a and exhaust air from the another end 19 b.Specifically, the first exhaust pipe 19 sucks in the air from theaccommodating space S and exhausts the air to the outside through thecooling fan 11.

The second exhaust pipe 20 is a substantially linear pipe having one end20 a and another end 20 b. The one end 20 a of the second exhaust pipe20 is located in the engine room 9, and the another end 20 b of thesecond exhaust pipe 20 is located in the cooling room 10. The secondexhaust pipe 20 passes through the partition wall 9 b to extend in thefront-back direction on the left side and above the engine room 9 andthe cooling room 10.

The one end 20 a of the second exhaust pipe 20 is disposed above theconnecting pipe 13 b. The one end 20 a of the second exhaust pipe 20 isdisposed between the diesel particulate filtering device 13 a and theselective catalyst reduction device 13 c in the plane view. One end part20 c that includes the one end 20 a of the second exhaust pipe 20 bendstoward the inside. Consequently, the one end 20 a of the second exhaustpipe 20 is located near the center in the vehicle width direction.

The another end 20 b of the second exhaust pipe 20 is located betweenthe cooling fan 11 and the cooling unit 18. Another end part 20 d thatincludes the another end 20 b of the second exhaust pipe 20 bendsdownward and to the inside so that the another end 20 b of the secondexhaust pipe 20 is located between the cooling fan 11 and the coolingunit 18. Since negative pressure occurs between the cooling fan 11 andthe cooling unit 18 as described above, the second exhaust pipe 20 sucksin air from the one end 20 a and exhausts air from the another end 20 b.

FIG. 7 is a perspective view of the top plate 9 c as seen from the leftrear. As illustrated in FIG. 7, the top plate 9 c is fixed in aremovable manner with screws and the like to the upper end part of thevehicle cover 9 a. The top plate 9 c is a plate-like member having afront part that projects upward, and includes a flat part 9 d, a firstsloping part 9 e (example of a sloping part), a pair of side wall parts9 f, a front wall part 9 n (see FIG. 2), and a second sloping part 9 g.

The flat part 9 d is rectangular, extends substantially horizontally,and defines the front part upper plane of the engine room 9. An exhaustpipe 9 h extends upward from the flat part 9 d. The exhaust pipe 9 h isa pipe for exhausting the exhaust gas that has been processed from theexhaust gas post-processing device 13 to the outside. As illustrated inFIG. 2, the front wall part 9 n extends from the front edge of the flatpart 9 d downward toward the vehicle cover 9 a.

As illustrated in FIG. 7, the first sloping part 9 e extends to the rearfrom the rear edge of the flat part 9 d, and the height decreasestowards the rear. The first sloping part 9 e has the same width as theflat part 9 d and defines the rear part upper plane of the engine room9. The first sloping part 9 e has a first ventilation part 9 i made upof a plurality of through-holes. Air inside the engine room 9 isexhausted to the outside, and outside air is sucked into the engine room9 through the first ventilation part 9 i. The through-holes thatconstitute the first ventilation part 9 i have a slit shape.

The pair of side wall parts 9 f extends downward from both edges of theflat part 9 d and the first sloping part 9 e toward the vehicle cover 9a. The side wall parts 9 f each have a flange part 9 p at the loweredges. The side wall parts 9 f each have a second ventilation part 9 jmade up of a plurality of through-holes. Air inside the engine room 9 isexhausted to the outside, and outside air is sucked into the engine room9 through the second ventilation parts 9 j. The through-holes thatconstitute the second ventilation parts 9 j have a slit shape.

FIG. 8 is a cross-section of the left side of the side wall part 9 f asseen from the rear. As illustrated in FIG. 8, the through-holes thatconstitute the second ventilation parts 9 j each have an eave part 9 kat the upper part. By providing each of the through-holes with the eavepart 9 k at the upper part since the side wall parts 9 f substantiallyextend vertically, liquid such as rainwater can be prevented fromentering the engine room 9.

As illustrated in FIG. 7, a projecting part at the front of the topplate 9 c is configured by the abovementioned flat part 9 d, the firstsloping part 9 e, the pair of side wall parts 9 f, and the front wallpart 9 n. The capacity of the engine room 9 is increased by the amountof the space enclosed by the flat part 9 d, the first sloping part 9 e,the pair of side wall parts 9 f and the front wall part 9 n.

The second sloping part 9 g extends to the rear from the rear edges ofthe first sloping part 9 e and the flange parts 9 p. The height of thevehicle cover 9 a decreases toward the rear, and the second sloping part9 g slopes along the upper edge of the rear part of the vehicle cover 9a. Specifically, the height of the second sloping part 9 g decreasestoward the rear. The slope of the second sloping part 9 g is gentlerthan the slope of the first sloping part 9 e.

The second sloping part 9 g mainly defines an upper plane of the coolingroom 10, and partially defines the rear part upper plane of the engineroom 9. The second sloping part 9 g has an intake part 9 m made up of aplurality of through-holes. When the cooling fan 11 is operating, airinside the cooling room 10 is exhausted to the outside through anopening part of the grille 21, and outside air is sucked into thecooling room 10 through the intake part 9 m. Further, air from theoutside flows into the cooling room 10 through an intake part 9 q formedin the vehicle cover 9 a.

FIG. 9 is a side cross-section of a drainage mechanism 15 disposedinside the rear vehicle body 3 b as seen from the left side. Tofacilitate explanation, the description of the first exhaust pipe 19 isomitted in FIG. 9. As illustrated in FIG. 9, the drainage mechanism 15is disposed inside the engine room 9. The drainage mechanism 15 includesa receptacle member 15 a and a water conveyance member 15 b.

The receptacle member 15 a is disposed below the first ventilation part9 i of the first sloping part 9 e, and is a tray-like member thatreceives rainwater and the like that enters the engine room 9 from thefirst ventilation part 9 i. The receptacle member 15 a has a rectangularbottom plate 15 c and a side plate 15 d that extend upward from theouter edges of the bottom plate 15 c. The width of the receptacle member15 a is the same or greater than the width of the first ventilation part9 i so as to be able to receive all the rainwater entering through thefirst ventilation part 9 i, and is preferably approximately the samewidth as the engine room 9. The front edge of the receptacle member 15 ais located at the front edge of the first ventilation part 9 i orlocated further forward than the front edge of the first ventilationpart 9 i. The rear edge of the receptacle member 15 a is located at therear edge of the first ventilation part 9 i or further to the rear ofthe rear edge of the first ventilation part 9 i, and is preferablylocated near the partition wall 9 b. The bottom plate 15 c is disposedin a sloped manner so that the height of the bottom plate 15 c is lowerfurther toward the rear in order to allow the rainwater received by thereceptacle member 15 a to flow toward the rear.

FIG. 10 is a perspective view of the drainage mechanism 15 as seen fromthe right rear, and FIG. 11 is a perspective view of the waterconveyance member 15 b disposed on the left side as seen from the rightrear. To facilitate explanation, the description of the second slopingpart 9 g on the top plate 9 c, and the first and second exhaust pipes 19and 20 are omitted in FIGS. 10 and 11. As illustrated in FIG. 10, thebottom plate 15 c of the receptacle member 15 a has through-holes 15 eat a left rear edge part and at a right rear edge part. The waterconveyance members 15 b are disposed below each of the through-holes 15e. The water conveyance member 15 b disposed on the left side of theengine room 9 and the water conveyance member 15 b disposed on the rightside of the engine room 9 have symmetrical shapes relative to the centerin the vehicle width direction, and therefore only an explanation of thewater conveyance member 15 b disposed on the left side will be providedhereinbelow.

The water conveyance member 15 b is a member that guides rainwater thatdrips from the through-holes 15 e of the receptacle member 15 a to theoutside of the engine room 9. As illustrated in FIGS. 9 and 11, thewater conveyance member 15 b has a bottom plate 15 f and a side plate 15g. The bottom plate 15 f is rectangular, and the left edge of the bottomplate 15 f is fitted to the vehicle cover 9 a, and the rear edge of thebottom plate 15 f is fitted to the partition wall 9 b. The side plate 15g extend upward from the front edge and the right edge of the bottomplate 15 f Specifically, the water conveyance member 15 b is avessel-shaped member that is open at the upper plane, and the lowerplane is defined by the bottom plate 15 f and the side planes aredefined by the side plate 15 g, the vehicle cover 9 a, and the partitionwall 9 b.

The partition wall 9 b is a plate-like member for separating the engineroom 9 and the cooling room 10, and has notch-like water drainageoutlets 9 r at a right upper edge part and at a left upper edge part.The upper edge of each water drainage outlet 9 r is located higher thanthe bottom plate 15 f of the water conveyance member 15 b, and thebottom edge of each water drainage outlet 9 r is located lower than theupper edge of the side plates 15 g. The water conveyance member 15 b isdisposed in a sloped manner so that the height of the bottom plate 15 fis lower further toward the rear in order to allow the rainwaterreceived by the receptacle member 15 a to flow to the rear. As a result,the rainwater that drips off of the receptacle member 15 a into thewater conveyance members 15 b flows toward the rear and is dischargedthrough the water drainage outlets 9 r of the partition wall 9 b towardthe cooling room 10.

The receptacle member 15 a is located below the first sloping part 9 eas illustrated in FIG. 2. The receptacle member 15 a is located abovethe diesel particulate filtering device 13 a. The receptacle member 15 ahas heat insulation properties. For example, the receptacle member 15 amay be formed of a steel plate treated with a heat insulating coating,may be formed of aluminum, an aluminum alloy, or stainless steel, or maybe coated with a coating including aluminum, an aluminum alloy, orstainless steel. The transmission of radiant heat from the dieselparticulate filtering device 13 a to the top plate 9 c can be suppressedby the receptacle member 15 a that is disposed between the dieselparticulate filtering device 13 a and the top plate 9 c. In this way,the receptacle member 15 a functions as a heat insulating plate.

Characteristics

The wheel loader 1 according to the present embodiment has the followingcharacteristics.

(1) The another end 19 b of the first exhaust pipe 19 is located betweenthe cooling unit 18 and the cooling fan 11 which is a region of negativepressure when the cooling fan 11 is operating. As a result, the firstexhaust pipe 19 acts to suck in the air around the injection device 14from the one end 19 a and to exhaust the air from the another end 19 b.Consequently, the area around the injection device 14 in the engine room9 has negative pressure, and the air taken in from outside of the engineroom 9, for example, through the first and second ventilation parts 9 iand 9 j of the top plate 9 c flows around the injection device 14. As aresult, the injection device 14 is cooled by the cooling air that flowsfrom the outside toward the one end 19 a of the first exhaust pipe 19.

(2) The front and rear of the injection device 14 is covered by therespective peripheral wall parts 16 b and 17 b of the first and secondpartition plates 16 and 17. As a result, the one end 19 a of the firstexhaust pipe 19 is able to effectively suck in air around the injectiondevice 14 and accordingly is able to further cool the injection device14. Furthermore, since the second partition part 16 b 1 of theperipheral wall part 16 b of the first partition plate 16 is disposedbetween the injection device 14 and the selective catalyst reductiondevice 13 c, radiant heat radiating from the selective catalystreduction device 13 c to the injection device 14 can be blocked.Accordingly, a rise in the temperature of the injection device 14 due toradiant heat from the selective catalyst reduction device 13 c can beprevented. Further, since the peripheral wall part 17 b of the secondpartition plate 17 is disposed between the injection device 14 and thediesel particulate filtering device 13 a, radiant heat radiating fromthe diesel particulate filtering device 13 a to the injection device 14can be blocked. According to this configuration, a rise in thetemperature of the injection device 14 due to radiant heat from thediesel particulate filtering device 13 a can be prevented.

(3) The injection device 14 is disposed between the connecting pipe 13 band the vehicle cover 9 a. As a result, the area around the injectiondevice 14 is covered by the connecting pipe 13 b and the vehicle cover 9a in addition to the abovementioned respective peripheral wall parts 16b and 17 b of the first and second partition plates 16 and 17.Consequently, the first exhaust pipe 19 is able to suck the air aroundthe injection device 14 from the one end 19 a more effectively to allowfor more cooling of the injection device 14.

(4) The another end 20 b of the second exhaust pipe 20 is locatedbetween the cooling unit 18 and the cooling fan 11 which is a region ofnegative pressure when the cooling fan 11 is operating. As a result, thesecond exhaust pipe 20 acts to suck in air inside the engine room 9 fromthe one end 20 a and exhaust the air from the another end 20 b.Consequently, hot air inside the engine room 9 can be exhausted to theoutside.

(5) The front, the rear, and the top of the injection device 14 iscovered by the respective peripheral wall parts 16 b and 17 b of thefirst and second partition plates 16 and 17. Consequently, the firstexhaust pipe 19 is able to suck in the air around the injection device14 from the one end 19 a more effectively to allow for more cooling ofthe injection device 14.

(6) Since mainly the rear part of the top plate 9 c of the engine room 9is provided with the sloping part 9 e in which the height decreasestoward the rear, the visibility to the rear can be assured even thoughthe top plate 9 c of the engine room 9 is high. Since the firstventilation part 9 i is formed in the sloping part 9 e, the occupiedsurface area of the first ventilation part 9 i can be made wider than ifthe first ventilation part 9 i is formed in a horizontal portion, andthe intrusion of rainwater can be suppressed.

(7) The capacity of the engine room 9 is increased by the amount inwhich the front part of the top plate 9 c projects upward.

(8) Since the top plate 9 c has the second ventilation part 9 j inaddition to the first ventilation part 9 i, air is able to flow moresmoothly between the inside and the outside of the engine room 9. As aresult, the injection device 14 can be cooled more effectively.

(9) Since the second ventilation part 9 j has the eave parts 9 k, theintrusion of rainwater through the second ventilation part 9 j into theengine room 9 can be suppressed.

MODIFIED EXAMPLES

While an embodiment of the present invention has been described above,the present invention is not limited to the embodiment and manyvariations and modifications can be made within the spirit of thepresent invention.

Modified Example 1

While the partitioning member is configured of two partition platesbeing the first partition plate 16 and the second partition plate 17 inthe above embodiment, the number of partition plates that configure thepartitioning member is not limited as such and the partitioning membermay be configured of one partition plate or may be configured of threeor more partition plates. Specifically, the injection device 14 may becovered by one partition plate or may be covered by three or morepartition plates. The first and second partition plates 16 and 17 thatconstitute the partitioning member may be omitted.

Modified Example 2

The front, rear and the top of the injection device 14 is covered by,but not limited to, the respective peripheral wall parts 16 b and 17 bof the first and second partition plates 16 and 17 in the aboveembodiment. For example, the front, the rear, the top, and the bottom ofthe injection device 14 may be covered by the respective peripheral wallparts 16 b and 17 b of the first and second partition plates 16 and 17,and further the right side of the injection device 14 may also becovered.

Modified Example 3

While two pipes constituted by the first exhaust pipe 19 and the secondexhaust pipe 20 are installed in the above embodiment, the secondexhaust pipe 20 may be omitted and only the first exhaust pipe 19 may beinstalled.

Modified Example 4

While the first and second ventilation parts 9 i and 9 j are formed inthe top plate 9 c to bring in outside air into the engine room 9 in theabove embodiment, the present invention is not limited as such. Forexample, a ventilation part may be formed in the vehicle cover 9 a thatdefines the side surface of the engine room 9 instead of being formed inthe top plate 9 c. In this case, forming the ventilation part in aregion of the vehicle cover 9 a facing the injection device 14 isdesired from the point of view of effectively cooling the injectiondevice 14.

Modified Example 5

While an example of a wheel loader has been explained in the aboveembodiment, the present invention may be applicable to another workvehicle.

1. A work vehicle comprising: an engine; an exhaust gas post-processingdevice including a diesel particulate filtering device, a selectivecatalyst reduction device, a connecting pipe connecting the dieselparticulate filtering device and the selective catalyst reductiondevice, and an injection device configured and arranged to inject areducing agent into the connecting pipe; an engine room accommodatingthe engine and the exhaust gas post-processing device; a cooling fanconfigured and arranged to suck in air from one side and to exhaust airfrom another side to produce an air flow; a cooling unit disposed on theone side of the cooling fan; and a first exhaust pipe having one endconfigured and arranged to suck in air around the injection device andanother end located between the cooling fan and the cooling unit; a topplate defining an upper plane of the engine room; a cooling roomdisposed to the rear of the engine room and accommodating the coolingunit; and a partition wall separating the engine room and the coolingroom; wherein the exhaust gas post-processing device is disposed abovethe engine, and the top plate has a first ventilation part including aplurality of through-holes communicating the engine room with anoutside.
 2. The work vehicle according to claim 1, further comprising apartitioning member including a first partition part disposed betweenthe injection device and the diesel particulate filtering device, and asecond partition part disposed between the injection device and theselective catalyst reduction device.
 3. The work according to claim 1,wherein the one end of the first exhaust pipe is located above anattachment part of the injection device to the connecting pipe.
 4. Thework vehicle according to claim 2, wherein the one end of the firstexhaust pipe is located in an accommodating space defined by the firstpartition part and the second partition part.
 5. The work vehicleaccording to claim 1, further comprising a second exhaust pipe havingone end located above the connecting pipe inside the engine room andanother end located between the cooling fan and the cooling unit.
 6. Thework vehicle according to claim 1, wherein the connecting pipe isdisposed so that a longitudinal direction thereof is aligned in avehicle width direction, and the injection device is disposed on a firstside of the connecting pipe as seen from a rear of the work vehicle. 7.The work vehicle according to claim 6, wherein the injection device isconfigured and arranged to inject the reducing agent at an upstream sideof the exhaust gas flowing inside the connecting pipe.
 8. The workvehicle according to claim 6, wherein the diesel particulate filteringdevice and the selective catalyst reduction device are disposed withlongitudinal directions thereof aligned in the vehicle width direction.9. The work vehicle according to claim 2, wherein the injection deviceis disposed between the diesel particulate filtering device and theselective catalyst reduction device in a front-back direction of thework vehicle; and the partitioning member includes a third partitionpart disposed above the injection device.
 10. (canceled)
 11. The workvehicle according to claim 1, wherein the top plate further has asloping part having a height that decreases toward a rear of the workvehicle; and the first ventilation part is formed in the sloping part.12. The work vehicle according to claim 11, wherein the sloping part ofthe top plate defines a rear part upper plane of the engine room, andthe top plate further includes a flat part extending horizontally to afront of the work vehicle from a front edge of the sloping part, theflat part defining a front part upper plane of the engine room.
 13. Thework vehicle according to claim 12, wherein the top plate furtherincludes a pair of side wall parts extending downward from both sideedges of the flat part and the sloping part, and each of the side wallparts includes a second ventilation part including a plurality ofthrough-holes.
 14. The work vehicle according to claim 13, wherein eachof the through-holes of the second ventilation part has an eave part.15. (canceled)
 16. A wheel loader comprising: an engine; an exhaust gaspost-processing device including a diesel particulate filtering device,a selective catalyst reduction device, a connecting pipe connecting thediesel particulate filtering device and the selective catalyst reductiondevice, and an injection device configured and arranged to inject areducing agent into the connecting pipe; an engine room accommodatingthe engine and the exhaust gas post-processing device; a cooling roomdisposed to the rear of the engine room and accommodating a coolingunit; a partition wall separating the engine room and the cooling room;a cooling fan disposed to the rear of the cooling unit in the coolingroom and configured and arranged to exhaust air inside the cooling roomto the rear; a first exhaust pipe having one end configured and arrangedto suck in air around the injection device and another end displacedbetween the cooling fan and the cooling unit; and a top plate definingan upper plane of the engine room; wherein the exhaust gaspost-processing device is disposed above the engine, and the top platehas a first ventilation part including a plurality of through-holescommunicating the engine room with an outside.